Unique does not properly describe this type of circuit. Most of the usual suspects (Analog Devices, Maxim, National, etc.) produce devices that will certainly work with that level of input. They also go very low voltage and even higher voltage with lower currents.

Advanced or innovative would be better adjectives to use. The good news is that you get that cutting edge technology at a relative low per unit cost.

It is true that some portion of the operating temperature range will completely swamp the OP's input power and uses most of that power over the rest. I know that it is not really efficient for 10V 4mA but I found this one after only a few minutes search. The last time I did any real research into this type of circuit was a couple of years ago. The goal was 5V 2mA. I remember I found something that may have worked even that low but it was cost prohibitive so we just went with a larger battery.

A two chip solution would probably be best. Use the same technique but have the charge operation completely shut down during capacitor charging from a harvester. Boosting to a higher intermediate capacitor voltage would probably help.